The present invention involves a monoclonal antibody (MAb) with the specificity for a 67,000 dalton cell surface protein of Streptococcus pneumoniae, a cell line that produces said antibody, and the partially purified 67,000 dalton cell surface protein.
S.pneumoniae is the leading cause of community-acquired bacterial pneumonia (pneumococcal disease) with approximately 500,000 cases a year reported in the United States. Bacterial pneumonia is the most prevalent among the very young, the elderly and immuno-compromised persons. In infants and children, pneumococci are the most common bacterial cause of pneumonia, otitis media and bacteremia and a less common cause of meningitis (causing 20-25% of reported cases).
Pneumococci are carried in the respiratory tract of a significant number of healthy individuals. In spite of the high carriage rate, its presence does not necessarily imply infection. However, if one of the highly pathogenic pneumococcal types, such as S.pneumoniae, is isolated from rusty-coloured sputum (also containing a large number of polymorphonuclear leucocytes), body fluids, blood cultures, or specimens collected via transtracheal or lung puncture from the lower respiratory tract, its detection is usually significant.
Detection of this bacteria at an early stage is essential to facilitate treatment of the infection. Thus, it is important to possess the ability to identify whether S.pneumoniae is present in a patient and to be able to follow the effect of antibiotic treatment on the bacteria. As available immunoassays for S.pneumoniae antigen detection have shown lack of specificity and/or sensitivity, there remains the need for an improved method of such detection.
S.pneumoniae is a gram positive bacteria. Proteins located on the cell surface of many gram positive bacteria have, in the past, been used in typing and immunoprotection studies. There are a large number of S.pneumoniae strains, and there are many cell surface proteins associated with S.pneumoniae. This has made the identification of a common but exclusive cell surface antigen difficult. However, MAb technology has provided researchers with tools to reproducible and accurately analyze the cell surface components of S.pneumoniae. In addition, S.pneumoniae proteins are of interest to epidemiologists as they may provide for vaccines against the bacteria.
One such pneumonococcal capsular polysaccharide vaccine has been developed, which incorporates the polysaccharide antigen of 23 serotypes of pneumococci that are responsible for 87% of pneumococcal disease in the United States. This second generation vaccine replaced the 14-valent polysaccharide vaccine licensed in 1977. However, the U.S. Department of Health and Human Services states that a more immunogenic pneumococcal vaccine is needed, particularly for children younger than 2 years of age. This is because the 23-valent vaccine is poorly antigenic in this age group, and its use is not recommended in children with recurrent upper respiratory diseases, such as otitis media and sinusitis. Furthermore, the 23-valent vaccine is only 44-61% efficacious when administered to persons over 65 years old, and revaccination is not advised. Thus, there remains the need for an improved pneumococcal vaccine.
It follows then, that there remains a need for at least two products relating to S.pneumoniae. The first is a rapid, specific, and sensitive diagnostic technique for of all strains of S.pneumoniae, that does not give false positive results. What is optimally desired is a Mab that will recognize a cell surface antigen that is universally present in most, if not all, strains of S.pneumoniae and, at the same time does not recognize other organisms or material which may be found in conjunction with S.pneumoniae. Secondly, it is desirous that the Mab and said 67,000 dalton protein be used in research towards development of an improved vaccine.